I've determined the problem to be the lock has seized and prevents me from opening the door
Are you talking about the lock itself (where the key goes) ? If so, you can remove the outside lock from the interior mechanism. If you look at the back of the lock, there should be a little C-clip on it (fi I remember correctly). You can remove the clip, the the rod should be able to be taken off the lock. I had to do the same on the driver door, but I did it a couple of months ago, so not sure if there is something else besides the clip. Once the clip and the rod is off, you can then unlock the door from the inside and the door should open.